Cold planers, also known as pavement profilers, road milling machines or roadway planers, are machines designed for scarifying, removing, mixing or reclaiming material from the surface of bituminous or concrete roadways and similar surfaces. Cold planers typically have a plurality of tracks or wheels which adjustably support and horizontally transport the machine along the surface of the road to be planed. Cold planers also have a rotatable planing rotor or cutter that may be mechanically or hydraulically driven to grind up and scrape off the top surface of the road over which the cold planer is driven. As the rotor grinds up the surface of the road, conveyors at the front of the cold planer transport the loose material and dump it into the bed of a truck driving in front of or to the side of the cold planer.
The tracks or wheels and the rotor of the cold planer are driven by an engine of the machine. The cold planer includes additional components and systems that draw power from the engine when operated to perform various functions of the cold planer. Many components function together to regulate the amount of material removed by the rotor, and to contain the removed material and transport the material to the collection vehicle. For example, vertical adjustment of the cold planer with respect to the road surface may be provided by hydraulically adjustable struts or legs that support the cold planer above its tracks or wheels. The legs are extended and retracted to control the depth to which the rotor grinds into the surface. Sideplates disposed on either side of the rotor are raised and lowered to provide a visual depth reference as the cold planer moves across the surface as well as providing lateral enclosure of the rotor and containment of the removed material. The sideplates are typically part of the grade control system and serve as the grade reference used by the control system. A moldboard behind the rotor is positioned at a depth lower than the bottom surfaces of the sideplates to scrape up the loose material and clean the surface so minimal additional cleanup is necessary after the cold planer makes a pass over the surface of the road. An anti-slab in front of the rotor and proximate the first stage conveyor is positioned just above the top surface of the road to break up the material and prevent the rotor from lifting up large chucks of material that are not readily conveyable. A second stage conveyor transports the material up from the first stage conveyor and dumps it into the truck. The second stage conveyor is moved up and down to change its angle and from side to side to properly position the top of the conveyor based on the height and position of the truck. The legs, sideplates, moldboard, anti-slab and conveyors may be driven by hydraulically, with the hydraulics being operated by a common pump that is powered by the engine. Cold planers usually include additional components drawing power from the engine, such as lights, generators and air compressors.
Many of the components of the cold planer may be operated while the cold planer is idling. For example, the positions of the legs, sideplates, moldboard, anti-slab and second stage conveyor may be adjusted before engaging the rotor and making a pass over a surface. Moreover, the rotor may be engaged or disengaged when the engine is idling and not being propelled. The engine speed required to provide adequate pressurized fluid flow for driving the various components to perform the functions of the cold planer varies based on the component being operated, and the combinations of components that are simultaneously being powered by the engine. The lights, generators and air compressors may require minimal power and low engine speeds to operate. In contrast, operating the legs to raise or lower the cold planer simultaneously with repositioning the second stage conveyor may require a greater amount of power via pressurized fluid flow that is supplied by running the engine at a higher engine speed. The operator does not always know the optimum engine speed necessary for performing the functions, and is typically not able to make constant adjustments to the engine speed. The operator may run the engine at a speed that is too low to meet the needs of the operations or, more likely, may run the engine at a higher speed than is required to meet the need such that fuel is wasted and more sound is generated.
In view of this, a need exists for an engine speed management control system for cold planers that is capable of selecting an optimum engine speed for performing the requested operations based on the operations that are being requested, while allowing the operator the ability to override the engine speed to a higher idle where maximum response and cycle times in performing the operations is required.